1 /* 2 * CPU subsystem support 3 */ 4 5 #include <linux/kernel.h> 6 #include <linux/module.h> 7 #include <linux/init.h> 8 #include <linux/sched.h> 9 #include <linux/cpu.h> 10 #include <linux/topology.h> 11 #include <linux/device.h> 12 #include <linux/node.h> 13 #include <linux/gfp.h> 14 #include <linux/slab.h> 15 #include <linux/percpu.h> 16 17 #include "base.h" 18 19 struct bus_type cpu_subsys = { 20 .name = "cpu", 21 .dev_name = "cpu", 22 }; 23 EXPORT_SYMBOL_GPL(cpu_subsys); 24 25 static DEFINE_PER_CPU(struct device *, cpu_sys_devices); 26 27 #ifdef CONFIG_HOTPLUG_CPU 28 static void change_cpu_under_node(struct cpu *cpu, 29 unsigned int from_nid, unsigned int to_nid) 30 { 31 int cpuid = cpu->dev.id; 32 unregister_cpu_under_node(cpuid, from_nid); 33 register_cpu_under_node(cpuid, to_nid); 34 cpu->node_id = to_nid; 35 } 36 37 static ssize_t show_online(struct device *dev, 38 struct device_attribute *attr, 39 char *buf) 40 { 41 struct cpu *cpu = container_of(dev, struct cpu, dev); 42 43 return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id)); 44 } 45 46 static ssize_t __ref store_online(struct device *dev, 47 struct device_attribute *attr, 48 const char *buf, size_t count) 49 { 50 struct cpu *cpu = container_of(dev, struct cpu, dev); 51 int cpuid = cpu->dev.id; 52 int from_nid, to_nid; 53 ssize_t ret; 54 55 cpu_hotplug_driver_lock(); 56 switch (buf[0]) { 57 case '0': 58 ret = cpu_down(cpuid); 59 if (!ret) 60 kobject_uevent(&dev->kobj, KOBJ_OFFLINE); 61 break; 62 case '1': 63 from_nid = cpu_to_node(cpuid); 64 ret = cpu_up(cpuid); 65 66 /* 67 * When hot adding memory to memoryless node and enabling a cpu 68 * on the node, node number of the cpu may internally change. 69 */ 70 to_nid = cpu_to_node(cpuid); 71 if (from_nid != to_nid) 72 change_cpu_under_node(cpu, from_nid, to_nid); 73 74 if (!ret) 75 kobject_uevent(&dev->kobj, KOBJ_ONLINE); 76 break; 77 default: 78 ret = -EINVAL; 79 } 80 cpu_hotplug_driver_unlock(); 81 82 if (ret >= 0) 83 ret = count; 84 return ret; 85 } 86 static DEVICE_ATTR(online, 0644, show_online, store_online); 87 88 static void __cpuinit register_cpu_control(struct cpu *cpu) 89 { 90 device_create_file(&cpu->dev, &dev_attr_online); 91 } 92 void unregister_cpu(struct cpu *cpu) 93 { 94 int logical_cpu = cpu->dev.id; 95 96 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 97 98 device_remove_file(&cpu->dev, &dev_attr_online); 99 100 device_unregister(&cpu->dev); 101 per_cpu(cpu_sys_devices, logical_cpu) = NULL; 102 return; 103 } 104 105 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 106 static ssize_t cpu_probe_store(struct device *dev, 107 struct device_attribute *attr, 108 const char *buf, 109 size_t count) 110 { 111 return arch_cpu_probe(buf, count); 112 } 113 114 static ssize_t cpu_release_store(struct device *dev, 115 struct device_attribute *attr, 116 const char *buf, 117 size_t count) 118 { 119 return arch_cpu_release(buf, count); 120 } 121 122 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store); 123 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store); 124 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ 125 126 #else /* ... !CONFIG_HOTPLUG_CPU */ 127 static inline void register_cpu_control(struct cpu *cpu) 128 { 129 } 130 #endif /* CONFIG_HOTPLUG_CPU */ 131 132 #ifdef CONFIG_KEXEC 133 #include <linux/kexec.h> 134 135 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr, 136 char *buf) 137 { 138 struct cpu *cpu = container_of(dev, struct cpu, dev); 139 ssize_t rc; 140 unsigned long long addr; 141 int cpunum; 142 143 cpunum = cpu->dev.id; 144 145 /* 146 * Might be reading other cpu's data based on which cpu read thread 147 * has been scheduled. But cpu data (memory) is allocated once during 148 * boot up and this data does not change there after. Hence this 149 * operation should be safe. No locking required. 150 */ 151 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum)); 152 rc = sprintf(buf, "%Lx\n", addr); 153 return rc; 154 } 155 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL); 156 157 static ssize_t show_crash_notes_size(struct device *dev, 158 struct device_attribute *attr, 159 char *buf) 160 { 161 ssize_t rc; 162 163 rc = sprintf(buf, "%zu\n", sizeof(note_buf_t)); 164 return rc; 165 } 166 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL); 167 #endif 168 169 /* 170 * Print cpu online, possible, present, and system maps 171 */ 172 173 struct cpu_attr { 174 struct device_attribute attr; 175 const struct cpumask *const * const map; 176 }; 177 178 static ssize_t show_cpus_attr(struct device *dev, 179 struct device_attribute *attr, 180 char *buf) 181 { 182 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr); 183 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map)); 184 185 buf[n++] = '\n'; 186 buf[n] = '\0'; 187 return n; 188 } 189 190 #define _CPU_ATTR(name, map) \ 191 { __ATTR(name, 0444, show_cpus_attr, NULL), map } 192 193 /* Keep in sync with cpu_subsys_attrs */ 194 static struct cpu_attr cpu_attrs[] = { 195 _CPU_ATTR(online, &cpu_online_mask), 196 _CPU_ATTR(possible, &cpu_possible_mask), 197 _CPU_ATTR(present, &cpu_present_mask), 198 }; 199 200 /* 201 * Print values for NR_CPUS and offlined cpus 202 */ 203 static ssize_t print_cpus_kernel_max(struct device *dev, 204 struct device_attribute *attr, char *buf) 205 { 206 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1); 207 return n; 208 } 209 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); 210 211 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ 212 unsigned int total_cpus; 213 214 static ssize_t print_cpus_offline(struct device *dev, 215 struct device_attribute *attr, char *buf) 216 { 217 int n = 0, len = PAGE_SIZE-2; 218 cpumask_var_t offline; 219 220 /* display offline cpus < nr_cpu_ids */ 221 if (!alloc_cpumask_var(&offline, GFP_KERNEL)) 222 return -ENOMEM; 223 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask); 224 n = cpulist_scnprintf(buf, len, offline); 225 free_cpumask_var(offline); 226 227 /* display offline cpus >= nr_cpu_ids */ 228 if (total_cpus && nr_cpu_ids < total_cpus) { 229 if (n && n < len) 230 buf[n++] = ','; 231 232 if (nr_cpu_ids == total_cpus-1) 233 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids); 234 else 235 n += snprintf(&buf[n], len - n, "%d-%d", 236 nr_cpu_ids, total_cpus-1); 237 } 238 239 n += snprintf(&buf[n], len - n, "\n"); 240 return n; 241 } 242 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); 243 244 static void cpu_device_release(struct device *dev) 245 { 246 /* 247 * This is an empty function to prevent the driver core from spitting a 248 * warning at us. Yes, I know this is directly opposite of what the 249 * documentation for the driver core and kobjects say, and the author 250 * of this code has already been publically ridiculed for doing 251 * something as foolish as this. However, at this point in time, it is 252 * the only way to handle the issue of statically allocated cpu 253 * devices. The different architectures will have their cpu device 254 * code reworked to properly handle this in the near future, so this 255 * function will then be changed to correctly free up the memory held 256 * by the cpu device. 257 * 258 * Never copy this way of doing things, or you too will be made fun of 259 * on the linux-kernel list, you have been warned. 260 */ 261 } 262 263 /* 264 * register_cpu - Setup a sysfs device for a CPU. 265 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 266 * sysfs for this CPU. 267 * @num - CPU number to use when creating the device. 268 * 269 * Initialize and register the CPU device. 270 */ 271 int __cpuinit register_cpu(struct cpu *cpu, int num) 272 { 273 int error; 274 275 cpu->node_id = cpu_to_node(num); 276 memset(&cpu->dev, 0x00, sizeof(struct device)); 277 cpu->dev.id = num; 278 cpu->dev.bus = &cpu_subsys; 279 cpu->dev.release = cpu_device_release; 280 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE 281 cpu->dev.bus->uevent = arch_cpu_uevent; 282 #endif 283 error = device_register(&cpu->dev); 284 if (!error && cpu->hotpluggable) 285 register_cpu_control(cpu); 286 if (!error) 287 per_cpu(cpu_sys_devices, num) = &cpu->dev; 288 if (!error) 289 register_cpu_under_node(num, cpu_to_node(num)); 290 291 #ifdef CONFIG_KEXEC 292 if (!error) 293 error = device_create_file(&cpu->dev, &dev_attr_crash_notes); 294 if (!error) 295 error = device_create_file(&cpu->dev, 296 &dev_attr_crash_notes_size); 297 #endif 298 return error; 299 } 300 301 struct device *get_cpu_device(unsigned cpu) 302 { 303 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 304 return per_cpu(cpu_sys_devices, cpu); 305 else 306 return NULL; 307 } 308 EXPORT_SYMBOL_GPL(get_cpu_device); 309 310 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE 311 static DEVICE_ATTR(modalias, 0444, arch_print_cpu_modalias, NULL); 312 #endif 313 314 static struct attribute *cpu_root_attrs[] = { 315 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE 316 &dev_attr_probe.attr, 317 &dev_attr_release.attr, 318 #endif 319 &cpu_attrs[0].attr.attr, 320 &cpu_attrs[1].attr.attr, 321 &cpu_attrs[2].attr.attr, 322 &dev_attr_kernel_max.attr, 323 &dev_attr_offline.attr, 324 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE 325 &dev_attr_modalias.attr, 326 #endif 327 NULL 328 }; 329 330 static struct attribute_group cpu_root_attr_group = { 331 .attrs = cpu_root_attrs, 332 }; 333 334 static const struct attribute_group *cpu_root_attr_groups[] = { 335 &cpu_root_attr_group, 336 NULL, 337 }; 338 339 bool cpu_is_hotpluggable(unsigned cpu) 340 { 341 struct device *dev = get_cpu_device(cpu); 342 return dev && container_of(dev, struct cpu, dev)->hotpluggable; 343 } 344 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); 345 346 #ifdef CONFIG_GENERIC_CPU_DEVICES 347 static DEFINE_PER_CPU(struct cpu, cpu_devices); 348 #endif 349 350 static void __init cpu_dev_register_generic(void) 351 { 352 #ifdef CONFIG_GENERIC_CPU_DEVICES 353 int i; 354 355 for_each_possible_cpu(i) { 356 if (register_cpu(&per_cpu(cpu_devices, i), i)) 357 panic("Failed to register CPU device"); 358 } 359 #endif 360 } 361 362 void __init cpu_dev_init(void) 363 { 364 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) 365 panic("Failed to register CPU subsystem"); 366 367 cpu_dev_register_generic(); 368 } 369